--- old/src/java.base/windows/classes/java/io/WinNTFileSystem.java	2017-06-27 12:02:11.315306300 -0700
+++ new/src/java.base/windows/classes/java/io/WinNTFileSystem.java	2017-06-27 12:02:10.893431300 -0700
@@ -29,6 +29,7 @@
 import java.nio.file.Path;
 import java.util.Locale;
 import java.util.Properties;
+import java.util.stream.IntStream;
 import sun.security.action.GetPropertyAction;
 
 /**
@@ -587,22 +588,12 @@
     @Override
     public File[] listRoots() {
         int ds = listRoots0();
-        int n = 0;
-        for (int i = 0; i < 26; i++) {
-            if (((ds >> i) & 1) != 0) {
-                if (!access((char)('A' + i) + ":" + slash))
-                    ds &= ~(1 << i);
-                else
-                    n++;
-            }
-        }
-        File[] fs = new File[n];
-        int j = 0;
-        char slash = this.slash;
-        for (int i = 0; i < 26; i++) {
-            if (((ds >> i) & 1) != 0)
-                fs[j++] = new File((char)('A' + i) + ":" + slash);
-        }
+        File[] fs = IntStream
+            .range(0, 26)
+            .filter(i -> ((ds >> i) & 1) != 0)
+            .mapToObj(i -> new File((char)('A' + i) + ":" + slash))
+            .filter(f -> access(f.getPath()) && f.exists())
+            .toArray(File[]::new);
         return fs;
     }